GPDs enter the DVCS cross section through integrals over the quark momentum fraction \(x\) , called Compton Form Factors (CFFs).
CFFs are defined in terms of the vector GPDs
\(H\)  and \(E\) , and the axial vector GPDs \(\widetilde{H}\)  and \(\widetilde{E}\) .
For example (\(f\in \lbrace u,d,s\rbrace \) ) [1]}:
\({\mathcal {H}}(\xi ,t) = \sum _{f} \left[\frac{e_f}{e}\right]^2\Biggl \lbrace i\pi \left[H_f(\xi ,\xi ,t) - H_f(-\xi ,\xi ,t)\right]\\+{\mathcal {P}}\int _{-1}^{+1} dx\left[ \frac{1}{\xi -x} - \frac{1}{\xi +x} \right] H_f(x,\xi ,t)\Biggr \rbrace ,\) 
